The present invention relates, in general, to the field of electric machines.
An electric machine can be operated at maximum power only when the temperature of various heat-producing machine components is monitored. Examples of heat-generating components include stator, rotor, winding, or bearing units. A particular important factor for the performance of an electric machine is hereby the maximally admissible winding temperature. Exceeding the admissible winding temperature can result in a destruction of the electric machine.
Typically, the temperature has been ascertained heretofore through the provision of temperature sensors that were integrated in a winding end portion or overhang. This approach suffers shortcomings because the thermal linkage of the sensor directly influences the quality of the measuring value, and since the temperature sensor has a predefined mass, it has a thermal time constant that prevents a correlation of the measuring value with the actual temperature value of the winding. Moreover, as the provision of an additional electric insulation of the temperature sensor is required, the time constant is increased, thereby further deteriorating the thermal linkage.
It would be desirable and advantageous to provide an improved electric machine which obviates prior art shortcomings and which is constructed with a temperature monitoring system that is simple in structure and yet reliable in determining an exact and current temperature to thereby allow operation of the electric machine at maximum capacity, even when the electric machine runs in a highly dynamic manner.